As is well known, surgical instruments used in the healthcare industry must be sterilized before and/or after each use. Sterilization, of course, frees instruments from microorganism contamination, to prevent infections and the spread of diseases among patients. All medical procedures rely upon a stringent program of sterilization.
The medical device industry has addressed the sterilization requirements in the surgical field by offering two general types of surgical instruments: reusable instruments and single use, or disposable, instruments. Reusable instruments are typically composed of stainless steel and are typically sterilized before their initial use and then cleaned and resterilized prior to each subsequent use thereof. Single use or disposable instruments, on the other hand, are often fabricated primarily from plastic materials, thereby reducing costs associated with manufacture, and are discarded after use in a single procedure.
With respect to reusable surgical instruments, e.g., forceps, graspers, dissectors, probes, hemostats, scissors and the like, sterilization and resterilization had historically been accomplished using various sterilization modalities. In a broad sense, these sterilization processes generally involve placing instruments to be sterilized in a tray, wrapping the instruments and the tray with a sterilization wrap, and placing the wrapped tray and instruments in a sterilization chamber, where the instruments are exposed to a sterilization medium. In order to protect the instruments, a tray liner is typically placed on the tray, and then the surgical instruments are placed on the tray liner. In order to protect the tray itself, the tray is typically placed on corner guards or a base pad before it is wrapped and placed in the sterilization chamber.
One long and continuing problem encountered with sterilization, however, is the presence of moisture that remains on the sterilized instruments, i.e., within the sterile wrap, at the conclusion of the sterilization process. This residual moisture can range from slight levels of dampness to visible droplets on the surface of surgical instruments. Such residual moisture is both undesirable and is unacceptable because such moisture could permit migration of surface microorganisms, thereby penetrating the wrapped tray or basin and rendering its contents contaminated, and/or may cause rust or pitting of the surgical instruments. Also, the wrapped tray may become stained during sterilization or even torn during loading or removal from a sterilization chamber because of the damp condition of the sterilization wrap.
Tray liners formed of a single material, such as open or closed cell foam or a cellulose based material have been employed in the past. For example, a hydrophilic polyurethane foam trayliner is disclosed in U.S. Pat. No. 6,902,712, incorporated herein by reference. This tray liner is comprised of a single foam layer. While effective, the evaporation rate and dispersing properties of foam liners could be improved to allow for more efficient moisture absorption and multiple applications within in a sterilization system.
Two-ply liners comprised of foam backing are known in the art. Typically a foam layer is adhered to plastic or cloth. However, use of adhesive to join liners used for sterilization presents several problems. The adhesive may deteriorate when exposed to high heat, steam and/or various chemicals used in the sterilization process. The liners may delaminate or adhesive may come in contact with the sterile instruments or sterilizing equipment. The adhesive residue is often sticky and difficult to eliminate.
In addition, laminated paper products which contain at least one layer of paper bonded to a foam layer have also been known for some time. See e.g. U.S. Pat. Nos. 3,687,797; 3,285,800; 3,530,030; 3,366,532. However, these multi-layered products are also adhered together with an adhesive or thermally fused with hot rollers. U.S. Pat. No. 4,276,339 discloses a more efficient lamination process via a gelling process; however it does not allow the paper and foam to be separately purchased.
A two-ply liner comprised of foam and paper joined by flame lamination has never been taught for the purpose moisture trapping, and more specifically for use in sterilization of surgical instruments.